Install and configure MariaDB Galera 4 cluster on Centos 7 in VirtualBox

Background: Clustering is used to achieve High Aaailability(HA) in many forms and is widely used in database technologies to meet the service uptime and to load balance clients requests. We will see how to configure a Opensource Galera cluster on MariaDB database. This documents assume that you are familiar with virtualization technologies especially VirtualBox, you…

Oracle table partitioning: why, when and how

Why partitioning: Enhances the performance, manageability, and availability. Partitioning allows tables, indexes, and index-organized tables to be subdivided into smaller pieces. When to partition a table: Tables larger than 2gb size. Historical data Contents must be stored in different storage Avoid index maintenance when data is removed Index maintenance on parts of data like rebuilding…

Migrating Bitnami WordPress website from AWS EC2 to VPS Bitnami NGINX

Steps to perform during migration: Install VPS with CentOS 7 without any LAMP stack. configure the x11 window and forwarding make a directory named as /bitnami to be used as installed directory Download the WordPress NGINX stack installer from bitnami. Login as root user, installation should be done as root user to avoid later complexities.…

Enabling tracing for oracle LISTENER

Background: For the oracle errors like “ORA-12170: TNS:Connect timeout occurred”, “ORA-12535: TNS:operation timed out”, “ORA-12560: TNS:protocol adapter error”, “TNS-00505: Operation timed out” and like others related to oracle listener it is useful of tracing the listener activities to dig down further. Workaround: Connect to the listener control utility from the command line or shell. LSNRCTL…

Linked tables having Calculated field can’t be made Local in MS Access 2016

Background: For the purpose of taking backup of the MS access database, VBA script failed for one of the tables of the source database, showing “Property not found Error: 3270“. Resolution: Compact and repairing didn’t solve the issue, recreated the table also didn’t help. Upon further dig down its been observed that removing the “Calculated”…

Cloning a virtual machine in VirtualBox

Background Cloning of a virtual machine is the easiest way around to get the copy of the same operating system environment which saves time and effort of another installation and configuration of the same. Workaround Choose the virtual machine that should be cloned. Right click on the VM and select “Clone”.                                              Provide the “Name”, “Path”…

Create an ECS Linux instance in OpenStack based Fusion Cloud

What is an ECS? ECS stands for Elastic Cloud Server that facilitates computing needs for applications, technically it is a virtual machine in cloud environment. Steps to create an ECS: Determine the resource required like cpu, memory and storage. Determine the Operating System images with required version. For networking create a VPC if not already…

Configure sending mail by sendmail in Ubuntu Linux

Background: I need email functionality to send emails from the web server by querying data from MySQL database and email the result to appropriate recipient. Workaround:  Install sendmail. sudo apt-get update sudo apt-get install sendmail Install mailutils. sudo apt-get install mailutils Configure the /etc/hosts file, provide your domain name in the following format 127.0.0.1 localhost…